Brain Arousal Karius T#2

Question 1

What two parts make up consciousness?

Answer 1

• Arousal (being awake)
• Awareness

Question 2

What is a coma?

Answer 2

person is neither awake or aware with absence of sleep and wake cycles

Question 3

What is a persistance vegetative state?

Answer 3

• physiologically identifiable sleep wake cycles-you see REM
• NO evidence of awareness

Question 4

What is a minimally conscious state?

Answer 4

• sleep wake cycles
• reproducible evidence of awareness-can respond to simple commands
• limited or absent communication

Question 5

In a persistance vegetative state damage to what section of the brain is more common?

Answer 5

small lesions in:

• brainstem
• midbrain
• hypothalamus

also shown that cortical neurons are up to 30 mV below threshold—very hyperpolarized

Question 6

Describe the EAA, what does it mean by saying this is the most basic?

Answer 6

It works on the Reticular activating system and the parabrachial nuclei in the pons.

Has to be present and functional to move from comatose to persistant vegetitave state

Question 7

What is the cholinergic arousal system?

Answer 7

Pedunculopontine tegmental and laterodorsal nuclei, basic (EAA) needed

Question 8

What is the significance of the noradrenergic, serotonergic and dopaminergic arousal systems?

Answer 8

They lead to greater levels of consciousness

• noradrenergic: Locus ceruleus
• Serotonergic: raphae nuclei
• Dopaminergic: ventral tegmental area

Question 9

Where is the EAA located>

Answer 9

Mid ventral portion of the medulla and midbrain, it is a loose collection of neurons and fiber tracts

Question 10

What is the does the EAA recieve?

Answer 10

Recieves ALL ascending sensory tracts also recieves trigeminal, ,auditory, and visual information

Question 11

Whta does it mean in the RAS for modal specificity to be lost?

Answer 11

All info convertges on the same neurons so the brain only knows that something happened, but it doesn’t recognize the difference between the visual, auditory trigeminal or sensory tracts.

Question 12

How does information get from the RAS to the cortex?

Answer 12

• Dorsal pathway: RAS sends axon to non specific nuclei of the thalamus using excitatotry aa which then sends an axon to cortex
• Ventral pathway:RAS sends axon straight to cortex, bypassing thalamus, using excitatory aa

Question 13

How do you get from comatose to a persistant vegetattive state?

Answer 13

By having an acitive EAA therefore RAS and pararbrachial nuclei

Question 14

Where is wthe parabrachial nuclei located and what system is it a part of?

Answer 14

• Located in the pons
• Part of EAA
• Recieves almost all of the same sensory inputs that the RAS receives

Question 15

Outputs from the parabrachial nuclei?

Answer 15

Exclusively ventral pathway, so it bypasses the thalamus and sends axons dierectly to the cortex and uses excitatory aa such as glutamate

Question 16

What two parts make up the cholinergic arousal system, what is the NT, what paths?

Answer 16

• Pedunculopontine tegmental and laterodorsal nuclei, which recieve so much input same as EAA that they lose modal input. They only know that something happend.
• uses dorsal and ventral outputs, but uses Ach!

Question 17

How do you move from persistant vegetative state to awareness

Answer 17

• Needs EAA and Cholinergic to be vegetative
• To move to awareness you need noradrenergic also

Question 18

Where is the Noradrenergic system located?

Answer 18

• Locus Cereuleus which recieves sensory from a lot of places
• However, it is processed information, not like EAA/Chol.:
  
  • Paragigantocellularis
  • Periaqueductal grey
  • Higher centers including the cortex

Question 19

How do outputs from the locus cereuleus send info to cortex?

Answer 19

• dorsal path
• ventral path

Question 20

What are the functions of the LC NA system?

Answer 20

• Startle and alerting responses on the EEG
• sleep-wake
• produce behavioural vigilance

Question 21

Where does the serotonergic input come from?

Answer 21

Raphe Nuclei located at the midline

Question 22

What are the inputs from the serotonergic system?

Answer 22

• Sensory from spinal cord- very specific information

Question 23

What are the outputs for the serotonergic system?

Answer 23

• Dorsal and ventral pathways
• Other outputs related to function

Question 24

What function does serotonin give?

Answer 24

• Quiet awareness
• Mood and affect modulation of pain are non RAS activities

Question 26

To move from general awareness to actual alertness what is needed

Answer 26

Dopaminergic system from the ventral tegmental area

Question 27

The ventral tegmental area provides dopaminergic input that is important for?

Answer 27

• Cognitive functions
• motor activity
• emotion

Question 28

What are the neurons from the thalamus to cortex called?

Answer 28

Thalamocortical neurons, these are present in the dorsal pathway

Question 29

Where do the synapses occur in the dorsal pathway?

Answer 29

• Non-specific nuclei of the thalamus

Question 30

What do the thalamocortical neurons with EAA input synapse on in the cortex?

Answer 30

GABAergic neurons which cause alternating waves of excitation due to the EAA and inhibition due to the GABA realeased. This leads to waves being recorded on the EEG showing sleep wake cycles

Question 31

In a persistant vegetative state what happens to rostral regions of pons idbrain and thalamus show?

Question 32

In alzheimer’s disease what system is hit hard?

Answer 32

The cholinergic systems. Mental processses slow dramatically and memory formation is imparied in absence of excitation

Question 33

The noraderenergic and serotonergic systems move from awake to generally aware of information.

Question 34

What does an alerting response in an EEG indicate?

Answer 34

That the cortex is looking for sensory input

Question 35

How do thalamocortical neurons show action potentials?

Answer 35

During sleep the neurons are hyperpolarized, which cuts the cotrtex off from the excitatory influence during deepest levels of sleep